KR0183123B1 - Method of manufacturing biodegradable loose-fill - Google Patents

Abstract

The present invention relates to a method for producing a biodegradable packaging buffer material as a product directly foamed by an extruder by mixing a single or two or more of a physical reinforcing agent, a plasticizer, an extrusion lubricant and a foam control agent to starch and glycine derivatives thereof. It has a good appearance and excellent mechanical properties (compressive strength and restoring force) as well as a method for producing a packaging buffer material that is completely biodegradable by natural microorganisms.

That is, in order to improve the compressive strength and the restoring force of the buffer for packaging, firstly, a modified starch which is plasticized to starch by chemically esterifying glycine as a plasticizer, or using pure starch alone or a mixture of pure starches. Third, a method of manufacturing by adding a lignosulfonate to the furnace, and third, in addition to the method of using a homopolymer in the addition of polyvinyl alcohol (polyvinylalcohol (PVA) of the polymeric plasticizer, a copolymer (copplumer) is used. Fourth, characterized in that the method for producing a biodegradable packaging buffer by controlling the expansion rate (expansion rate) using an inorganic salt as a foaming regulator in the starch and starch-glycine derivatives.

The packaging buffer prepared by the present invention has a good appearance and has a dense structure and excellent mechanical properties, and is a product that can effectively reduce plastic waste, which is a problem recently, by being completely biodegraded by natural microorganisms.

Description

Manufacturing method of biodegradable packaging buffer

The present invention is a natural polymer using starch and its glycine derivatives (glycine derivatives), such as foaming, dense organization, low density, compressive strength and restoring power of existing expanded polystyrene (expand polystyrene, EPS, aka loose-fill, loose-fill) and The present invention relates to a method for preparing a packaging buffer material having similar appearance and mechanical properties and completely biodegraded by natural microorganisms.

Plastics are used every year due to various advantages, and in proportion to this, the amount of plastic discarded after use is increasing, accounting for about 25% of the total plastic use and environmental pollution.

In other words, the disposal method of plastic waste discarded after use is incinerated or landfilled like various wastes, and in the case of landfilling, it is hardly decomposed by transition metals or microorganisms present in the soil. It is known that it causes a large amount of gas and causes a global warming as well as a harmful effect on the human body.

In order to effectively dispose of plastic waste, research on materials that are similar to those of existing plastics and can be decomposed by natural microorganisms is being actively conducted. That is, aliphatic polyester through organic synthesis and polyhydroxyalkanoate by microbial fermentation (poly (hydroxy-alkanoate), PHA], polyhydroxybutylate [poly (hydroxy-butyrate), PHB] Biodegradable plastics prepared by adding a metal radical catalyst to a biodegradable plastic such as a composite of cellulose or starch, a natural polymer, and a nonpolar polyolefin resin, and a cellulose or starch added to a photodegradable plastic and a nonpolar polyolefin resin. It can be divided into sex plastic.

Active research is being conducted on biodegradable polymers containing starch which are abundant in nature and inexpensive.

However, starch is not thermoplastic, and it is a hydrophilic substance that contains 10 to 13% of water in itself and is not compatible with nonpolar polyolefin resin and aliphatic polyester. It is known to add up to 30% and molding compounds up to 70%.

On the other hand, in the present invention, in the preparation of a biodegradable packaging buffer material, the water contained in the starch is used as the most effective plasticizer, and as a synergist, it is completely decomposed by natural microorganisms using polymeric plasticizers and other additives. It is characterized by manufacturing a product.

To date, researches and manufacturing methods for biodegradable packaging buffers have been made using extruder by adding plasticizer to high amylose starch (more than 45% amylose content) or derivatives thereof (USP 4,863,655, EP 0375831 AI) Process for the preparation of alcohol derivatives (JP Hei-136168), Process for the preparation of foamed polyurethane substitutes using reactants of lignocellulosic and aliphatic polycols contained in wood flour or chaff (KP 95-18201), Starch And a method of preparing a mixture of a plasticizer and an inorganic salt with partially dextrinized starch or a derivative thereof (WO 92/18325, JP Hei 6-271695). The above methods have advantages in that the manufacturing method is simpler and does not use Freon gas, compared to the existing expandable polystyrene and polyurethane, while the price is high and the appearance, strength, and resilience are lowered compared to the conventional packaging buffer. There is this.

Therefore, in order to solve the problems of the conventional biodegradable packaging buffer material, the packaging buffer material which is completely biodegraded by natural microorganisms when disposed after use without deterioration in appearance and mechanical properties (compressive strength and restoring force) does not cause environmental problems. To provide a method that can be manufactured more easily and cheaply.

Therefore, the present invention is a product foamed directly with an extruder by mixing a single or two or more of a physical reinforcing agent, a plasticizer, an extrusion lubricant and a foam control agent to starch and its glycine derivatives and is completely biodegradable by natural microorganisms as well as good appearance and mechanical properties It is a method of manufacturing this excellent packaging cushioning material.

That is, in order to improve the compressive strength and the restoring force of the packaging buffer material, first, a method of using starch-glycine derivatives in which the hydroxy group of the starch is esterified with the carboxyl group of glycine, a plasticizer, or a mixture of pure starches that do not react, and secondly, To prepare a biodegradable packaging buffer by adding lignosulfonate, which is a natural substance, to starch and starch-glycine derivatives, and third, to add polyvinyl alcohol (polyvinylalcohol, PVA) in the polymeric plasticizer. Method of preparing biodegradable packaging buffers by adding copolymers in addition to using conventional homopolymers; fourth, foaming rate using inorganic salts as foam control agents for starch and starch-glycine derivatives to control biodegradable packaging buffers It shall be.

Referring to the manufacturing method of the biodegradable packaging buffer according to the present invention in more detail.

That is, as a method for preparing a glycine derivative of starch, water is added to the starch to prepare a starch suspension, and then glycine is added and stirred for 10 to 20 minutes. In this case, the allowable concentration range of the total solids is 10 to 50% (w / w), and 20 to 40% is appropriate in terms of reaction efficiency, and the amount of glycine added may be selected in an appropriate ratio depending on the reaction temperature and the degree of substitution required. However, 5 to 15% (w / w) relative to starch solids is preferred. Subsequently, the pH of the starch suspension was adjusted to a range of 7.5 to 13.0 using sodium hydroxide, calcium hydroxide and alkaline salts thereof as a reaction catalyst, and then the reaction was maintained at a temperature of 30 to 65 ° C. for 1 to 36 hours. After washing with water and drying to obtain the desired starch-glycine derivative, the reaction time is preferably 1.5 to 3.5 hours in view of production cost and efficiency.

The starch-glycine derivative prepared by the above method may be used alone or at least one of corn starch, waxy corn starch, potato starch, tapioca starch, sweet potato starch, wheat starch and rice starch in proportion to the mixer (V-mixer). ) And add 0.1-10% (w / w) of lignosulfonate as a physical property reinforcing agent and in the homopolymer and copolymer of polyvinyl alcohol, a polymeric plasticizer, polyvinylacetate, polyethylene acetate and polyethyleneacrylic acid copolymer. 1 to 45% (w / w) of at least one, monoacylglycerol (glycerol monopalmitate, glycerol mono stearate, glycerol monooleate, succinic acid ester of glycerol mono palmitate), and diacylglycerol in glycerol fatty acid ester 1-10% (w / w) extrusion lubricant and magnesium chloride, calcium carbonate, potassium carbonate, sodium carbonate, calcium phosphate, calcium chloride, etc. Adding a salt 0.1~10% (w / w) was added and then mixed for one hour and 30 minutes. Subsequently, the water content of the mixture was adjusted to 10-30% (w / w), and the barrel temperature was 120-300 ° C. and the screw speed 30-300 rpm using an extruder (screw diameter: 50 mm, L / D: 10-25). Biodegradable packaging buffer was prepared under the processing conditions of.

In addition, the evaluation of mechanical properties and biodegradability of the biodegradable packaging buffer according to the present invention was carried out by the following method.

[Resiliency]

Restorative force is the most important physical property required for packing cushioning material. It shows the degree of recovery to the original state after deformation by a constant force.

Resiliency test was performed by using a rheometer (cylinderical probe, diameter 20mm) attached to a sample (50mm diameter 13mm, length 20mm) at a rate of 0.5mm per second and then fixed for 1 minute. After the compression was again measured 10 times per sample the average value was represented by the restoring force by the following equation.

[Compressibility]

The compressive strength was measured under the same conditions as the measurement of the restoring force using a rheometer as a force required to deform the packaging buffer.

That is, the sample cut to 20 mm was attached to the rheometer sample stage, and the sample was deformed to yield stress (降伏 點) while moving at a speed of 0.5 mm per second. At this time, the highest force (g / cm 2) applied to the packaging buffer was measured 10 times and the average value was taken.

[Biodegradability]

Biodegradability evaluation of the biodegradable packaging buffer was determined by modifying the American Standard Test Methods (ASTM) G21-70 and 1924-70.

In other words, a fungus commonly found in soil after putting a sample cut to a certain size into a solid agar medium, Aspergillus niger, Aspergillus oryzae, Penicillium funiculosum (Penicillium funiculosum) ) And inoculated mixed spores such as Pulluaria pululans and incubated at 32 ℃ (± 2 ℃) for 30 days to evaluate.

As a result of evaluating the mechanical properties and biodegradability of the biodegradable packaging buffer prepared by the above method, it is possible to produce a dense product due to the even dispersibility of the starch, and the restoring force and the compressive strength are similar to those of the conventional polystyrene packaging buffer. In addition to being effectively degraded by natural microorganisms.

Therefore, the present invention can solve the environmental problems such as incineration, recovery, landfill pollution by replacing the expanded polystyrene used as a buffer for disposable packaging, it can contribute to the increase of export as part of measures in accordance with environmental regulations of the world.

Hereinafter, the present invention will be described in detail with reference to Examples, and the present invention is not limited to the following Examples.

Example 1

30 kg of starch of 13.3% moisture was added to a 200 L pilot pilot tube, and 108 L of water was added thereto, followed by stirring for 10 minutes. An additional 2.34 kg of glycine was added as a reactant, followed by stirring for 10 minutes. Subsequently, the mixture was adjusted to pH9.0 using 8% sodium hydroxide solution (NaOH solution) with continuous stirring, and then reacted for 3 hours at 40 ° C. After dehydration, washing and drying with 40 ° C hot water to prepare a starch derivative having a water content of 10.9% It was.

Example 2

30 kg of starch of 13.3% water was added to a 200L volume pilot tube, and 128L of water was added thereto, stirred for 10 minutes, and 6.8 kg of glycine was added as a reactant, followed by stirring for 10 minutes. Subsequently, the mixture was adjusted to pH 10.0 using 8% sodium hydroxide solution (NaOH solution) and reacted at 55 ° C. for 2 hours, and then treated in the same manner as in Example 1 to prepare a starch derivative having 11.3% moisture.

Example 3

10 kg of modified starch obtained in Example 1 (water content 10.9%), 49 g of lignosulfonate, 294 g of homopolymer of polyvinyl alcohol (polyviny-lalcohol), and monoacyl in a U-type mixer 490 g of glycerol (monoacyl-glycerol) and 49 g of sodium carbonate (Na ₂ CO ₃ ) were added thereto, followed by stirring for 1 hour 30 minutes. The mixture was introduced into an extruder with a screw diameter of 50 mm and L / D15, and then adjusted to a cylinder temperature of 170 to 200 ° C., and the speed of the screw was set at 300 rpm to prepare a biodegradable packaging buffer.

The prepared biodegradable packaging buffer material was evaluated for mechanical properties (density, resilience and strength) and biodegradability by the method described above.

Example 4

5 kg modified starch obtained in Example 2 (water content 11.3%) and 5 kg pure pure starch (water content 13.3%) were added to a mixer, followed by 49 g of lignosulfonate, 294 g of polyvinyl alcohol homopolymer, and diacylglycerol. 490g and 49g of potassium carbonate (K ₂ CO ₃ ) were added thereto, stirred for 1 hour 30 minutes, and prepared in the same manner as in Example 3, to evaluate mechanical properties and biodegradability.

Example 5

Into the mixer, 10 kg of pure general starch (13.3% water content), 62 g of lignosulfonate, 520 g of polyvinyl alcohol homopolymer, 124 g of monoacylglycerol, 366 g of diacylglycerol, and 49 g of sodium carbonate were mixed and mixed for 1 hour and 30 minutes. Prepared in the same manner as 3 to evaluate the mechanical properties and degradability.

Example 6

5 kg modified starch obtained in Example 1 (water content 10.9%) and 5 kg pure pure starch (water content 13.3%) were added to a mixer, 79 g lignosulfonate, 360 g polyvinyl alcohol homopolymer, and polyvinyl alcohol copolymer (copolymer). ) 360 g, monoacylglycerol 124 g, diacylglycerol 366 g and sodium carbonate 49 g were added and mixed well for 1 hour 30 minutes. Thereafter, the preparation was carried out in the same manner as in Example 3 to evaluate mechanical properties and degradability.

Example 7

10kg pure starch (water content 13.3%), 200g lignosulfonate, 120g polyvinyl alcohol homopolymer, 360g polyvinyl alcohol copolymer, 124g monoacylglycerol, 366g diacylglycerol and 98g sodium carbonate in a mixer for 1 hour 30 minutes After mixing for the prepared in the same manner as in Example 3 to evaluate the mechanical properties and degradability.

Example 8

10 kg of high amylose starch (at least 45% amylose content, 12.5% moisture content), 49 g lignosulfonate, 120 g polyvinyl alcohol homopolymer, 360 g polyvinyl alcohol copolymer, 124 g monoacylglycerol and 98 g sodium carbonate were added to the mixer. After mixing well for 30 minutes, it was prepared in the same manner as in Example 3 to evaluate the mechanical properties and degradability.

Example 9

10 kg of modified starch (water content 10.9%) obtained in Example 1, 240 g of polyvinyl alcohol homopolymer, 240 g of polyvinyl alcohol copolymer, 124 g of monoacylglycerol, 46 g of diacylglycerol and 98 g of sodium carbonate were mixed well for 1 hour 30 minutes in a mixer. After mixing, the preparation was carried out in the same manner as in Example 3 to evaluate mechanical properties and degradability.

Example 10

5 kg of modified starch (moisture content 11.3%) and 5 kg pure pure starch (water content 13.3%) obtained in Example 2 were added to a mixer, followed by 98 g of lignosulfonate, 240 g of polyvinyl alcohol homopolymer, and 240 g of polyvinyl alcohol copolymer. , Monoacylglycerol 72g, diacylglycerol 24g and calcium phosphate 98g was mixed well for 1 hour 30 minutes in a mixer and prepared in the same manner as in Example 3 to evaluate the mechanical properties degradability.

Example 11

5 kg of modified starch (water content 11.3%) and 5 kg pure pure starch (water content 13.3%) obtained in Example 2 were added to a mixer, followed by 49 g of lignosulfonate, 1440 g of polyethylene vinyl acetate, 120 g of monoacylglycerol, and 49 g of sodium carbonate. After mixing for 1 hour 30 minutes was prepared in the same manner as in Example 3 to evaluate the mechanical properties and degradability.

The results of comparing the properties and biodegradability of the biodegradable packaging buffer prepared in the above example with the existing expanded polystyrene packaging buffer (expansion polystyrene loose-fill; EPS loose-fill) are shown in Table 1,2.

Index according to mold growth rate

0: 0% growth

1: less than 10% growth

2: 10 to 30% growth

3: 30 to 60% growth

4: More than 60% growth

Claims (7)

Starch and its derivatives, which are natural polymers, are used alone or in a mixture in a proportion of physical properties (0.1 to 50%, w / w), polymeric plasticizer (1 to 45%, w / w), extrusion lubricant (1 to 10%, w / w) and foaming regulators (0.1 to 10%, w / w) alone or in combination of two or more, and mixed directly and the total water content is adjusted to 10 to 30% directly in an extruder preheated to 130 to 300 ° C. A method of making a biodegradable packaging cushioning material by extruding. The method of claim 1, wherein the starch derivative is an esterification reaction by adding 5 to 15% (w / w) of glycine which is an amino acid to the starch, to produce a biodegradable packaging buffer material. The starch according to claim 1 or 2, wherein the starch is corn starch, waxy corn starch, potato starch, tapioca starch, high amylose starch, sweet potato starch, wheat starch, rice starch and modified starch thereof, that is, oxidized starch, acid treated starch. A method for producing a biodegradable packaging buffer using a mixture of ester starch, crosslinked starch, hydroxy alkyl starch or α-starch thereof. The method of claim 1, wherein the physical property enhancer uses lignosulfonate. The method of claim 1, wherein the polymeric plasticizer is a homopolymer and copolymer of polyvinyl alcohol, polyvinylacetate, polyethylenevinylacetate, polyethylene acrylic acid copolymer or a method for mixing and adding these to prepare a biodegradable packaging buffer. The method of claim 1, wherein the extrusion lubricant is a mixture of glycerol, monoacylglycerol and diacylglycerol alone or two or more kinds to prepare a biodegradable packaging buffer. The method of claim 1, wherein the foam control agent is magnesium chloride, calcium carbonate, potassium carbonate, sodium carbonate, calcium phosphate and calcium chloride or a mixture thereof.